Composite sheeting material and method of manufacture

ABSTRACT

A method of manufacturing a composite fluted sheeting material comprising at least two surfaces interspersed with a plurality of substantially parallel spaced webs forming a plurality of elongate semi closed cells ( 5 ), and a filler material set within said cells; the method including the steps of: (f) applying a blank fluted sheet to a receiving station ( 7 ); (g) preparing a filler material for delivery to a filling station; (h) moving said blank sheet and/or said filling station relative to each other such that said filling station moves in a linear direction transversely across the open ends of said elongate semi closed cells of said sheet; (i) dispensing said filler material to said cells; allowing said filler material to set.

This application is the U.S. National Phase of International ApplicationPCT/AU02/01747, filed 24 Dec. 2002, which designated the U.S.

INTRODUCTION TO THE INVENTION

This invention relates to sheeting materials incorporating a semi-closedcellular structure; including such products variously known asflute-board, core-board, corrugated board etc. In particular theinvention relates to an improvement to the above products and a methodof manufacturing such improved products.

BACKGROUND TO THE INVENTION

Sheeting materials as detailed in the introduction are popular productswhich find extensive use in industries as diverse as signage and generalconstruction. These materials are generally produced in planar formshaving at least two planar surfaces separated by a plurality of elongatewebs forming a parallel series of elongate flutes or cells open ateither end of the sheet. The flutes can be formed as an integral wholewith the webs welded to the planar surfaces or by various methods ofadhesion.

Such sheeting material exhibits a very high strength to weight ratiobased on the rigidity derived from the torsion box principal. However,the strength and rigidity is not uniform over the sheet and is mainlyfound along the length of the flute webs. Accordingly, such materialsexhibit a weakness when a bending moment is applied parallel to theflute webs, this weakness is found in the compression or failure of theplanar surface between webs either side of the bending moment. Of coursesheeting can be manufactured with cross web fluting to form completelyclosed cells, which result in the classic torsion box construction ofconsiderable strength and rigidity in all dimensions. However, such aconstruction technique is complex and considerably more expensive toprovide than the semi closed cell flutes of standard board considered sofar.

Notwithstanding the disadvantages of such standard board, it hasconsiderable merit and is available in a wide range of sizes, materialsand configurations.

One object of this invention is to improve on the currently availablematerials, particularly in a manner to greatly enhance the current usesavailable for such products.

STATEMENT OF INVENTION

In one aspect the invention provides a method of manufacturing acomposite fluted sheeting material comprising at least two surfacesinterspersed with a plurality of substantially parallel spaced websforming a plurality of elongate semi closed cells, and a filler materialset within said cells; the method including the steps of:

-   -   (a) applying a blank fluted sheet to a receiving station;    -   (b) preparing a filler material for delivery to a filling        station;    -   (c) moving said blank sheet and/or said filling station relative        to each other such that said filling station moves in a linear        direction transversely across the open ends of said elongate        semi closed cells of said sheet;    -   (d) dispensing said filler material to said cells;    -   (e) allowing said filler material to set.

The receiving station may include a transporting means which may be aconveyor adapted to move said blank fluted sheet in a linear directionco-planar with said sheet.

The filling station may be fixed relative to said receiving station.

The receiving station may be adapted to incline said sheet along thelongitudinal direction of said cells to facilitate gravity assisteddelivery of said filler to the cells where the filling station ispositioned at the elevated end of said sheets.

The conveyor may include an upper and lower conveyor belt for receivingthe upper and lower ends of said sheet. The upper conveyor may include asecond jockey conveyor opposing the upper so as to sandwich said sheetto ensure full control of said sheet as it passes said filling station.

The filling station may include a mixing means and an injection head.The mixing means is adapted to mix the components of said filler priorto dispersing via said injection head. The injection head may includeone or a plurality of nozzles adapted to cooperate with the open cellends of the blank sheet. The nozzles may be adapted to advance andretract from the open end of sheet and be provided with a complaintstopper to assist in sealing the nozzle to the open cell ends. Themovement of said injection head may be coordinated with the linearmovement of the sheet such that the injection head advances to seal theopen cell or a group of cells for filling, and then retracts to allowthe sheet to move and present the next group of open cells for filling.

The filling station may be supplied with filler via a pumping station.The pumping station may be adapted to supply the filling station with asuitable filler in sufficient quantity and quality to achieve thenecessary filling of each empty cell.

The filler material may be an expanding setting foam of the polyurethanetype.

The foam is most preferably a multicomponent admixture adapted for rapidand expanding setting once mixed.

The polyurethane component of the foam may be selected from POLYOL™forming the basis of the urethane foam and a suitable hardener. Thepreferred temperature of the polyurethane mix at injection into thecavities of the chute is approximately 22 degrees Centigrade.

In another aspect the invention provides a machine for use in accordancewith the methods of the invention, said machine comprising

-   -   (a) a receiving station adapted for receiving a blank fluted        sheet having elongate semi closed cells;    -   (b) a filling station for dispensing a filler into the cells of        said fluted sheet.

The receiving station may include an inclined loading table having aconveying system for moving said fluted sheet in a linear directiontransversely across the direction of said elongate cells.

The conveying system may include at least two conveyor belts at theupper and lower ends of the table to receive the upper and lower ends ofthe sheet applied to the receiving station.

The loading table is adapted for receiving a blank sheet and atransporting section adapted for moving the sheet in a controlled manneracross the filling station.

The transporting section of the receiving station may include a second“jockey” conveyor opposing the upper conveyor belt over the length ofthe transporting section so as to ensure that the sheet is rigidly heldand transported relative to the filling station to allow cooperationbetween the filling station and the sheet.

The filling station may be mounted to the receiving station in thevicinity of the transport section thereof for cooperation with the sheetmoving past the station.

The filling station may include a mixing means and an injection head.The injection head being adapted for reciprocating movement torepeatedly abut and withdraw from the open end of said sheet withoptional up and down movement to cater for multi layered sheeting. Themovement of the injector head may be coordinated with the movement ofthe sheet to ensure that filler is systematically injected intoconsecutive cells of the sheet.

The injector head may include one or a plurality of nozzles adapted toextend into the open cells of the board during filling and withdraw fromthe cells as the injector head is withdrawn.

The injector head may also include a stopper to seal the injectorhead/sheet interface.

The machine may also include a pumping station for supplying the fillercomponents to the filler station in the most preferred format.

The pumping station may include reservoir tanks for the fillercomponents with output plumbing and pumps to provide a supply of fillercomponents to the filling station. The reservoir tanks may includetemperature control means to govern the temperature of the fillercomponents as supplied to the filling station.

In another aspect the invention provides a composite sheet material whenmade in accordance with the previously described methods.

The invention will now be described with reference to the followingfigures which represent only one particularly preferred embodiment ofthe invention:

FIG. 1 shows a sample of the sheeting material used by the invention.

FIG. 2 shows a schematic representation of the method of the invention.

FIG. 3 shows a perspective view of the machine of the invention.

FIG. 4 shows a side view of the machine.

FIG. 5 shows a plan view of the receiving station.

FIG. 6 shows detail of the transporting means as a series of conveyors.

FIG. 7 shows the filling station.

FIG. 8 shows the injector head in detail including the mixing means.

FIG. 9 shows the pumping station.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to one particularlypreferred embodiment as detailed in the accompanying figures.

Referring firstly to FIG. 1, the component material on which theinvention is based is shown in FIG. 1, where a section of flute boardmaterial 1 is shown. The flute board material is formed as a semi-rigidsheeting material having a first planar surface 2 and a second planarsurface 3 separated by a plurality of parallel webs 4. The sheetingmaterial thereby provides a series of parallel semi-closed cell cavities5 running the length of the sheeting material. This sheeting material isreadily available and as previously described, finds many current usesand applications in industries. The current invention is concerned withthe use of this readily available and economical material as the initialcomponent of a composite sheet having greatly enhances qualities andengineering characteristics over the original flute board sheetingmaterial. The invention is concerned with providing a filling materialfor application to the semi-closed cell cavities of the sheet andincludes the methods and machinery involved in the skillful applicationof a suitable filler material to the cavities of the sheeting product.

Referring to FIG. 2, the method of the invention is shown in schematicform where the filler materials including components A and B aresupplied to a pump station for preparation and supply to a fillingstation. The filling station is adapted to mix the filler components andsupply them to an injector head for injection into the cavities of thesheet material. The sheet material is presented to the injector head byway of a receiving station which coordinates the movement of the sheetto ensure systematic and controlled dispensing of the filler material tothe cavities of the sheet.

The preferred filler material is a polyurethane foam of two componentswhich instantaneously react upon mixing to begin foaming, expanding andsetting. The particular viscosities and physical characteristics of thefoam during the finite setting period require careful monitoring and themethodology of the invention is concerned with the automated dispensingof the filler material such that it can be passively supplied to aninclined sheet in sufficient and precise quantities and in a controlledenvironment such that the filler material supplied to the inclinedcavities descends the length of the cavities by the action of gravity,without the need for pressure pumping and descends at a rate such thatthe foam begins to set as it reaches the bottom of the cavity andprogressively hardens and sets up the cavity such that the full lengthof the cavity is progressively sealed with the setting foam fillermaterial without causing air bubbles or loss of material down the openend of the cavity.

The method of the invention can be best understood with reference to theaspect of the invention including the machine for use in accordance withthe method of the invention.

Referring firstly to FIGS. 3, 4 and 5, various views of the machine ofthe invention are shown with the machine including an elevated andinclined receiving station 6 which provides an extended platformcomprising a loading table 7 and a transporting section 8. The receivingstation is provided with a lower conveyor 9 and an upper conveyor 10adapted and spaced to receive the upper and lower ends respectively of asheet of fluted board loaded on to said receiving station. The conveyorsare adapted to move the sheet across the receiving station such that thecavities 5 are positioned in the inclined orientation so as to provide aslope to assist in the passive dispensing of filler material into theopen cavities. The receiving station may be provided with an optionalheating area 12 to assist in ensuring the optimal temperature of thesheet is obtained prior to filling. The sheeting material moves underthe influence of the conveyors toward the transporting section 8 andupon reaching the transporting section, is engaged by a jockey conveyor13 which is positioned to oppose the upper conveyor 10. In this manner,the upper end of the sheet is securely held between the two upperconveyors as it is transported past the filling station 14. As the topend of the sheet must be carefully aligned during passage past thefilling station so as to allow accurate cooperation with dispensing ofthe foam filler, the top edge of a sheet must be carefully aligned andsquarely presented at a constant distance to the filling station. Theprogress of the sheet is monitored by laser sensors to ensure accuratealignment is maintained. The loading table is provided with a pair oftop roller bars 28 at a fixed position against which the sheet isabutted as it is placed on the upper conveyor and before being engagedby the jockey conveyor 13. The load table is also provided with a bottomroller bar 29 which is sprung and compliant so as to allow for anyvariations in the lower cut of the sheet and to ensure that the sheet isheld snugly against the top roller bar.

Referring now to FIG. 4, the angle of the receiving station 6 can beclearly seen in its most preferred angle of inclination. The receivingstation is however, pivoted at pivot point 15 so as to provide optionaladjustments to the angle of inclination if so required. The positioningof the sheet 1 on the receiving station and its relationship with thelower 9 and upper 10 conveyors and the bottom roller bar 29 acting as astop is clearly seen from this side view of the machine of theinvention.

In order to provide consistency of alignment of the top end of the sheetwith the receiving station 14, the receiving station is pivoted at point15 and provided with a “c” shaped top end 30, to which the jockeyconveyor 13 is attached. The pivot point 15 is provided at the top endof the table so as to minimise any alignment variations of the top sheetwith respect to the filling station. The receiving station is adjustedby way of gas struts which effectively make the receiving stationweightless and easy to adjust. In addition, the top “c” part of thereceiving station is adjustable with bearing guides and gas struts toaccommodate a variety of sheet thicknesses.

In order to assist in collection and disposal of waste filler that mayescape from the bottom of the sheet cavities, the receiving station isprovided with waste conveyors for receiving and transporting excessfiller. The waste conveyors may be covered with a polyethylene film andwaxed to aid in foam release.

Referring now to FIG. 5, the receiving station is shown in plan viewwhere the loading section 7 can be seen to comprise a sufficient lengthof the receiving station to comfortably and accurately receive the sheetmaterial and ensure adequate alignment with the lower 9 and upper 10conveyors. The transporting section 8 comprises the bulk of thereceiving station where the sheet is engaged by the upper and lowerconveyors and an additional jockey conveyor 13. The filling station 14is positioned approximately mid-way along the receiving station suchthat the sheet material is able to receive full support from thereceiving station as it moves past the filling station such that thefilling can be accomplished with the finished and filled sheet stillcompletely supported by the receiving station.

Referring now to FIG. 6, details of the conveying system are shown withan end view of the upper conveyor 10 and a jockey conveyor 13 shown. Thedistance between the upper conveyor and the opposing jockey conveyor issufficient to securely engage and transport the sheet past the fillingstation.

The movement of the conveyors is computer controlled to ensurecoordinated movement of the sheet as it passes the filling station.

Referring now to FIGS. 7 and 8, the filling station is shown inperspective view from the underneath and from the rear of the machine.The filling station 14 comprises a mixing tube 16 adapted for receivingthe filler components by way of supply hoses 17 and 18. The supply hosesfeed the resin and hardener components of the filler into the mixingtube which takes the form of an elongate tubular mixing device forthoroughly churning and mixing the components of the filler material.The resin component of the filler may be aerated by micro-air nucleationto give bulk and buoyancy to the resin material. The air nucleation isapplied after the resin is supplied to the filling station and prior toentry to the mixers tube where the degree of aeration may be balanced tothe pressure inside the mixing tube and manifold. The balancing of theair nucleation can be accomplished by adjusting the air nucleation jetsize and the air pressure. At the distal end 19 of the mixing tube isfitted an injector head 20 for receiving the mixed filler anddistributing same through a plurality of nozzles 21. The injector headis also provided with a compliant stopper 22 which is adapted tocooperate with the exposed ends of the sheet 1 to ensure leak-freedispensing of the filler into the sheet cavities 5. The filling stationis fitted relative to the receiving station by way of a mounting means23. The injector head and mixing means are adapted for axialreciprocating movement to and fro so as to allow the filling station tobe advanced and retracted to and from the sheet 1 as the sheet is movedprogressively across the transporting section 8 of the receivingstation. In addition, the injector head may be moved up and down toaccommodate double, triple etc layered sheeting. The use of double,triple, quadruple etc layered sheeting can provide additional strengthand flexibility in design and structural specifications and withsuitable adjustments and computer settings, the injector head can bemodified to move up and down and/or across, so as to fill the layers offluted board in a progressive manner, so as to minimise any potentialdistortion that may occur if an upper or lower layer were filled in itsentirety, prior to filling of any subsequent layers. In its mostpreferred form, such multiple layered sheeting would be filledprogressively up and down so as to effect a steady linear process acrossthe face of the board. In this manner, the filler material is suppliedunder moderate pressure only to the filling station and the sheetmaterial is progressed forward such that vacant cavities 5 are exposedto the injector head. The injector head is then advanced such that thestopper 22 is brought to bear on the end of the preferred number ofcavities, for example, four cavities. Once the injector head has beenbrought to bear on the cavities, the rubber stopper ensures a leak-freeseal and the nozzles 21 are sufficiently protruding from the injectorhead to ensure discreet dispensing of mixed filler material into theseparate cavities 5. At this stage, the filler material is passivelydispensed into the vacant cavities and the rate of dispensing issufficient to allow the cavity to fill up as the filler reacts towardsthe bottom of the cavity. Whilst the filler is dispensed into the opencavities passively, it is nevertheless injected at the maximum flow rategoverned by the viscosity and consistency of the pre set filler mixtureand the stopper 22 ensures that backsplash of the filler from the top ofthe cavity is prevented. The nozzles 21 can be provided in a variety ofsizes dependent on the choice of filler viscosity and consistency. Thenozzles 21 are provided on a manifold 31 which is adapted for readyremoval and cleaning to aid in maintenance. Once the cavity has beenfilled, the injector head is retracted and the sheet is then progressedto align the next block of cavities with the injector head which is thenadvanced to fill the next set of cavities.

In an additional step, the manufacturer of the fluted board mayincorporate the progressive filling of the cores or flutes of the boardand specifically omit the filling of one or more cores or flutes, so asto provide a finished product with compliance and flexibility about thevacant cores or flutes. In addition, such vacant cores or flutes, may beaccommodated by strengthening rods or other various physical orperformance specific devices down the vacant flutes, for example,electronic or electrical componenetry could be accommodated inaccordance with the final specifications for the product in question.

The start/stop motion of the machine and the repeated movement andabutting of the injector head against the sheet may pressure the sheetto slide down the table. Accordingly, the conveyors are provided with athick soft and tacky synthetic rubber sole to ensure adequate grip onthe sheets to prevent any such slip. The injector head and mixing meansmay be provided with air hose and washing hose facilities such that themixing tube and injector head can be cleaned after each production runto assist in routine maintenance.

The filling material is supplied by way of a pumping station which isdetailed in FIG. 9. The pumping station comprises two reservoir tanks,24 and 25 which receive the bulk components of the filler materials fromthe bulk supply. The bulk components of the filler materials may besupplied with low pressure nitrogen gas to ensure the contents remainmoisture free and create a positive pressure to feed the fillercomponents to the reservoir tanks. The filler material is mostpreferably a standard grade urethane foam of about 40 to 60 kg/m³. Thefiller material is made up of urethane foam, resulting from the reactionof the resin and hardener. The hardener can be selected from a range ofsolvent based or water based catalysts, dependent on the performancespecifications of the product required.

The reservoir tanks are provided with temperature control means toensure the components of the filler are at the optimum temperature.

In this manner, the make-up of the filler material can be fully andcarefully controlled so as to ensure the appropriate viscosity andtemperature of the filling material is supplied to the filling station.Upon mixing and dispensing into the cavities 5, the filler is caused toflow down the inclined cavities at an appropriate rate such that by thetime the filling material has almost reached midway along the cavity ithas set or began to foam into a cream consistency which immediatelybinds to the inside of the cavity. At that stage the foam begins toexpand both directions up and down the cavity to back fill to the topand bottom of the cavity and then set to a hard filler.

The methods and machinery of the current invention provide for the firsttime a practical and economical method of value adding to a currentlyobtainable flute board sheeting material. The resultant material whichforms part of the invention provides a highly rigid lightweight,durable, workable and robust building and construction material. Theenhanced composite sheet of the invention provides many advantages overthe currently available fluting materials including the ability to bewelded and joined, plus of course, the highly enhanced rigidity andstrength in all dimensions over that currently available from theuntreated fluting material.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

1. A method of manufacturing a composite fluted sheeting materialcomprising at least two surfaces interspersed with a plurality ofsubstantially parallel spaced webs forming a plurality of elongate semiclosed cells, and a filler material set within said cells; the methodincluding the steps of: (a) applying a blank fluted sheet to a receivingstation; (b) preparing a filler material for delivery to a fillingstation; (c) moving said blank sheet and/or said filling stationrelative to each other such that said filling station moves in a lineardirection transversely across the open ends of said elongate semi closedcells of said sheet; (d) dispensing said filler material to said cells;(e) allowing said filler material to set.
 2. A method according to claim1 wherein said receiving station includes a transporting means formoving said blank fluted sheet in a linear direction coplanar with saidsheet.
 3. A method according to claim 2 wherein said transporting meansincludes a conveyor means.
 4. A method according to claim 1 wherein saidfilling station is fixed relative to said receiving station.
 5. A methodaccording to claim 1 wherein said receiving station includes an inclinedloading table adapted to incline said sheeting material positionedthereon in a direction longitudinal to said cells.
 6. A method accordingto claim 5 wherein said fitting station is positioned at the elevatedend of said inclined sheets to facilitate gravity assisted delivery ofsaid filler to said cells.
 7. A method according to claim 3 wherein saidconveyor means includes a plurality of conveyors.
 8. A method accordingto claim 7 wherein said conveyors include an upper and lower conveyor toreceive the upper and lower ends of said sheet respectively.
 9. A methodaccording to claim 8 wherein the upper conveyor means includes a jockeyconveyor adapted to oppose said upper conveyor so as to sandwich theupper end of said sheet.
 10. A method according to claim 9 wherein saidjockey conveyor operates at least in the region of said filling station.11. A method according to claim 1 wherein said filling station includesa mixing means which may be a mixing tube, and an injection head.
 12. Amethod according to claim 11 wherein said injection head includes anozzle assembly configured to cooperate with the open cell ends of saidblank sheet.
 13. A method according to claim 12 wherein said nozzleassembly is adapted to move between an advanced and retracted positionso as to allow said nozzle assembly to be moved into and out of saidopen cells.
 14. A method according to claim 13 wherein said nozzleassembly includes a compliant stopper to assist in sealing at the opencell ends of said sheet during filling when said nozzle assembly is insaid advanced position.
 15. A method according to claim 12 wherein saidnozzle assembly includes one or a plurality of nozzles.
 16. A methodaccording to claim 13 wherein the movement of said injection head iscoordinated with the linear movement of said sheet such that theinjection head advances to seal the open cell or cells of said sheet forfilling and retracts to allow said sheet to move laterally and presentempty cells for filling.
 17. A method according to claim 1 wherein saidfiller material is delivered by a pumping station.
 18. A methodaccording to claim 1 wherein said filling material is an expandingsetting foam.
 19. A method according to claim 18 wherein said foam is apolyurethane.
 20. A method according to claim 19 wherein said foam isadapted for rapid and expanding setting once mixed.
 21. A methodaccording to claim 20 wherein said foam is based on polyurethane™ resinand a suitable hardener.
 22. A method according to claim 21 wherein saidresin is subjected to micro-air nucleation post supply to said fillingstation and prior to entry to said mixing tube.
 23. A method accordingto claim 1 wherein said filler is dispensed at a temperature of about 22degrees centigrade.
 24. A machine for use in accordance with the methodof claim 1 comprising: (a) a receiving station adapted for receiving ablank fluted sheet having elongate semi-closed cells; and (b) a fillingstation for dispensing a filler into the cells of said fluted sheet. 25.A machine according to claim 24 wherein said receiving station includesan inclined loading table and a transporting means for moving said blankfitted sheet in a linear direction coplanar with said sheet.
 26. Amachine according to claim 25 wherein said transporting means includes aconveyor means.
 27. A machine according to claim 26 wherein saidconveyor means includes two conveyor belts positioned at the upper andlower end respectively of said inclined loading table to receive theupper and lower end of said fluted sheet.
 28. A machine according toclaim 27 wherein said transporting means further includes a jockeyconveyor belt opposing said upper conveyor belt at least in the regionof said filling station.
 29. A machine according to claim 24 whereinsaid filling station is mounted to said receiving station.
 30. A machineaccording to claim 24 wherein said filling station includes a mixingmeans and an injection head.
 31. A machine according to claim 30 whereinsaid injection head is adapted for reciprocating movement to repeatedlyadvance toward and retract away from the open cells of said sheet.
 32. Amachine according to claim 30 wherein said injection head includes aplurality of nozzles adapted to extend into said open cells duringfilling and retract out of said open cells as the injector head iswithdrawn.
 33. A machine according to claim 30 wherein said injectorhead includes a stopper to seal the injection/sheet interface.
 34. Amachine according to claim 24 including a pumping station for supplyingfiller components to said filler station.
 35. A machine according toclaim 34 wherein said pumping station includes temperature controlledreservoir tanks for the filler components.
 36. A composite sheetmaterial made in accordance with the method of claim 1.